My biggest concern is that it started malfunctioning after about 100 rounds. If it was broken out of the box I would mark it down to a problem in manufacturing, the fact it worked for a while makes me concerned about a problem with engineering or materials. If it was put together incorrectly, it is fixable, if it is an engineering or material problem it’s just a matter of time before it happens again. Thus my worry about using it as a primary defense weapon.
I have an old beater Mossberg pump that has been mistreated by myself for the last 30 years and I bought it used. Never a hiccup.
Don’t cost nothing to give them a call and ask them. Might just give you a new gun.